Identifier: textbookofphysio1916howe (find matches)
Title: A text-book of physiology : for medical students and physicians
Year: 1916 (1910s)
Authors: Howell, William H. (William Henry), 1860-1945
Subjects: Physiology Medicine
Publisher: Philadelphia and London : W. B. Saunders Company
Contributing Library: Yale University, Cushing/Whitney Medical Library
Digitizing Sponsor: Open Knowledge Commons and Yale University, Cushing/Whitney Medical Library

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is a discharging9 129 130 PHYSIOLOGY OF CENTRAL NERVOUS SYSTEM. process through which an impulse is sent out from the cell toreach another neuron or a cell of some other tissue. The neuron,so far as conduction is concerned, shows a definite polarity,the conduction in the dendrites being cellulipetal, in the axons,cellulifugal. The neuron doctrine, so far as the name at least is concerned, dates froma general paper by Waldeyer,* in which the newer work up to that time wassummarized. The main facts upon which the conception rests were furnishedby His (1886), to Avhom we owe the generally accepted belief that the nervefiber (axis cylinder) is an outgrowth from the cell, and secondly by Golgi,Cajal, and a host of other workers, who, by means of the new method of Golgi,demonstrated the wealth of branches of the nerve cells, particularly of thedendrites, and the mode of connection of one nerve unit with another. Theview that these units are anatomically independent and on the embryological
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Fig. 59.- -Motpr cell, anterior horn of gray matter of cord. From human fetus (Lenhos-sek): * marks the axon; the other branches are dendrites. side are derived each from a single epiblastic cell (neuroblast) has provedacceptable and most helpful; but the validity of this hypothesis has beencalled into question from time to time. As was stated on p. 127, Bethe hasclaimed that in young animals the nuclei of the neurilemmal sheath mayregenerate a new nerve fiber containing axis cylinder and myelin sheath, andthis fact, if true, at once brings into question the hitherto accepted belief Deut. med. Wochenschrift, 1891, p. 50. PROPERTIES OF THE NERVE CELL. 131 that the axis cylinder can be formed only as an outgrowth from a nerve cell.Some histologists—Apathy, Bethe, Nissl—have also attacked the mostfundamental feature of the neuron doctrine—the view, namely, that eachneuron represents an independent anatomical element. These authorscontend that the neurofibrils of the axis cylinder p

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